Hitting a baseball or softball is one of the most challenging propositions in all of sport. Consistency and balance are two key factors for having a good swing and for being productive at the plate. Generally, balance comes first as it sets up a solid foundation for the remaining mechanics to take shape, such as the “cocking” of the hips, transferring of power from the legs through the body and to the bat, and following through. Once a player develops a balanced swing, consistency is short to follow.
Having a balanced swing also places a player in a good position for sprinting out of the batter's box after making contact with the ball. As baseball can be a game of inches and seconds in a “bang-bang” play, any wasted movement trying to regain balance out of the batter's box takes time to correct and may result in a hitter being thrown out.
Moreover, foot movement during the swing is instrumental in determining whether a swing is balanced or not, especially movement of the back foot. Many good hitters finish the swinging motion on the ball of their back foot, the foot rotated approximately 90°, and not far from where it started, if it moved at all. This places the hitter in the optimal position for accelerating out of the batter's box. When a hitter rotates the back foot over 90° it twists the knee. The player must then rotate the foot back before putting weight on it to push off when launching out of the batter's box towards first base. A balanced and consistent swing takes practice; therefore, a device that discourages rotation of the back foot over 90° will go a long way in making practice more effective.